Test result interpretation negative tTG-IGA, positive DGP-IgG

[RitaGee44]

My 11 year old has been having his bloods taken due to presentation of various symptoms, lethargy, cramps etc

In particular,  

Transglutaminase-IgA (tTG-IgA) AND deamidated gliadin peptide-IgG (DGP-IgG) antibody tests 

The first tTG-IGA result recorded 0

The first DGP-IgG result was positive

At this point we we were referred to the Gastro, whilst we waited 4 weeks for that appointment we were told to try and eat as much gluten as possible. When we saw the specialist they wanted a second blood test, plus the gene screen before seeing them again soon.

The second tTG-IGA result again recorded 0 (negative)

The second DGP-IgG result was a stronger positive then before.

We’re currently waiting on the gene test results but any insights much appreciated from those results? 

 

 

 

[GFinDC]

Hi RitaG,

The IgA and IgG are types of antibodies.  A positive means that antibodies are being produced in the body to attack the gluten eaten ( and the body itself).  Although there are multiple types of antibodies, it only takes one kind of antibody to cause damage.  Since the celiac antibodies are present, the next step is an endoscopy to check for celiac style damage to the small intestine lining.  If the gut damage is confirmed, that is considered proof of celiac disease.

Edited January 14, 2019 by GFinDC

[RitaGee44]

Thanks GFinDC,

You explained that well, I’ve been trying to get my head around it, all the abbreviations used throughout the literature just confuses me more!

So one or both positive needs further investigation? Is one type of antibody ‘superior’ than the other when identifying celiac disease? And why wouldn’t both be positive? 

Thanks again for your time! 

[ravenwoodglass]

Welcome to the board. You only need one test to be positive to have celiac. Did they test his total IGA? Some folks are deficient and that would make the IGA test useless. As to the gene testing do be aware that while rare there are other genes that are associated with celiac but they usually only test for DQ2 and DQ8. Gene testing is also not diagnostic as there are many with the genes that never develop celiac.

Usually with a positive test they will do an endoscopy. Keep in mind that the small intestine is long and damage can be patchy. A false negative is possible if they biopsy misses a damaged spot. After all celiac testing is done a good strict trial of the gluten free diet should be advised. Do use this time to ask any questions you need about what you need to do when you start the gluten free lifestyle. Also keep in mind that all first degree relatives should be tested for celiac when a family member is diagnosed even if not symptomatic.

Good luck, hope he is feeling better soon and that the doctors can give you clear answers.

[cyclinglady]

I test positive only to the DGP IgA (had the celiac antibodies tests many times).   Never had a positive on any of the other screening tests, yet my biopsies revealed moderate to severe patches of villi damage.  

https://celiacdiseasecenter.columbia.edu/sites/default/files/Diagnostic-Yield-of-Isolated-Deamidated-Gliadin-Peptide-Antibody-Elevation-for-Celiac-Disease.pdf

It should be confirmed that his Immunoglobulin A (IgA) function is working.  If not, any IgA type test would be invalid.  If he does not make IgA, then you can never have a positive IgA celiac test.  I suppose to save money, it makes sense to run the two tests your son had.  It catches most celiacs, but not all.  

[GFinDC]

Hi Rita,

I think you got some good explanations already.  But yes, any positive antibody is a problem.  Some people will be positive on all of them, some won't.  We are individuals and can differ in how our bodies respond to things.  Usually the DGP tests are considered more reliable and accurate.

Another thing to have checked is vitamin and mineral levels.  Since celiac damage can cause malabsorption it is possible to become low on several important nutrients.  Vitamin D and B-12 and iron are some frequent problems.

[RitaGee44]

Thanks so much everyone! I keep nodding my head with everything you say! His bloods show he is Vit D deficient, low normal in calcium, he also has ‘mild neutropenia’. So all the signs from the reading here seem to point that way, his specialist didn’t seem convinced though. ?‍♀️ I’ll be better informed and know the questions to ask now when I see them next, so thanks again, it’s much appreciated. 

[Cal4802]

On 1/14/2019 at 10:45 PM, RitaGee44 said:

Thanks so much everyone! I keep nodding my head with everything you say! His bloods show he is Vit D deficient, low normal in calcium, he also has ‘mild neutropenia’. So all the signs from the reading here seem to point that way, his specialist didn’t seem convinced though. ?‍♀️ I’ll be better informed and know the questions to ask now when I see them next, so thanks again, it’s much appreciated. 

I also didn't score positive on TTG IGA (only a "1", 4 or higher was positive) but my TTG IGG was "10", 6 or higher is positive. So I was told to avoid gluten but read conflicting things online. Seems like IGA is the more reliable one (and no I don't have a deficiency). Did you find anything else more about IGG? Is that elevated level alone enough for concern? 

[Fenrir]

I had a weak positive TTG and my DGP was very high, definitely Celiac. 

[Cal4802]

12 minutes ago, Fenrir said:

I had a weak positive TTG and my DGP was very high, definitely Celiac. 

I'm not familiar with DGP? 

I only was tested for TTG IGA and TTG IGG which I thought were the two standard tests. 

Also Gliadin (Deamidated) for IGG/IGA.. (which were negative). 

[Fenrir]

9 minutes ago, Cal4802 said:

I'm not familiar with DGP? 

I only was tested for TTG IGA and TTG IGG which I thought were the two standard tests. 

Also Gliadin (Deamidated) for IGG/IGA.. (which were negative). 

DGP= Deamidated Gliadin Peptide. 

Basics on celiac testing:
TTG IgG is typically the first test done because it is 93% sensative, meainng 93% of celiacs will be postitve (weak or strong positive). It is also 98% specific, meaning if positive 98% it's Celiac Disease causing it. 

EMA IgA is another test sometimes used becuase it's very specific (99%), however, it's not a good screening test because sensitivity can be as low as 70%, so it won't detect 30% of celiacs. 

DGP is the newest of the three and more sensative than the TTG and the best test for people low in IgA levels that will typically cause negative TTGs. It's also more specific than TTG as well. 

 

[cyclinglady]

4 hours ago, Fenrir said:

I had a weak positive TTG and my DGP was very high, definitely Celiac. 

But did you ever get positives on the IgG versions?  I think the uncertainty comes from negative celiac IgA tests but getting a positive on the IgG celiac tests.  

It is much less clear.  Another reason why celiac experts still recommend an endoscopy.  

[Cal4802]

3 minutes ago, cyclinglady said:

But did you ever get positives on the IgG versions?  I think the uncertainty comes from negative celiac IgA tests but getting a positive on the IgG celiac tests.  

It is much less clear.  Another reason why celiac experts still recommend an endoscopy.  

Yes my IGG was very high (over 6 is positive, I scored a 10). My IGA was only a 1 (4 or higher was positive). 

[cyclinglady]

2 minutes ago, Cal4802 said:

Yes my IGG was very high (over 6 is positive, I scored a 10). My IGA was only a 1 (4 or higher was positive). 

Yes, but I know an elevated TTG IgG or DGP IGG is possible, but normally that occurs when someone is IgA (Immunoglobulin A) deficient.  I was looking for elevated IGG and biopsy-confirmed.  

Changing the subject, are you feeling better on the diet?  I know it is pretty early on, but I hope you are seeing signs of improvement.  

[Fenrir]

16 minutes ago, cyclinglady said:

But did you ever get positives on the IgG versions?  I think the uncertainty comes from negative celiac IgA tests but getting a positive on the IgG celiac tests.  

It is much less clear.  Another reason why celiac experts still recommend an endoscopy.  

Yes, my IgG tests were postive but TTG IgG  was weak.

Sure, it should always be confirmed by endoscopy. I don't see an instance where you shouldn't confirm with EGD. 

[cyclinglady]

9 minutes ago, Fenrir said:

Yes, my IgG tests were postive but TTG IgG  was weak.

Sure, it should always be confirmed by endoscopy. I don't see an instance where you shouldn't confirm with EGD. 

But you have positive IgA tests too?  

Unfortunately, some people do not have good insurance coverage or none at all.  Others live in countries where there are long wait times for medical procedures, so their primary care physicians suggest trialing the diet.  Hoping for better blood tests or less invasive diagnostic testing.  

[Fenrir]

3 minutes ago, cyclinglady said:

But you have positive IgA tests too?  

Unfortunately, some people do not have good insurance coverage or none at all.  Others live in countries where there are long wait times for medical procedures, so their primary care physicians suggest trialing the diet.  Hoping for better blood tests or less invasive diagnostic testing.  

Yes, my IgA was positive too. 

I was meaning from a medical point of view, a EGD should be done. However, I think if the person can't afford that of course you're probably going to want to go gluten-free. Even if it were to turn out not to be celiac disease many diseases are improved by a gluten-free. 

[cyclinglady]

1 hour ago, Fenrir said:

Yes, my IgA was positive too. 

I was meaning from a medical point of view, a EGD should be done. However, I think if the person can't afford that of course you're probably going to want to go gluten-free. Even if it were to turn out not to be celiac disease many diseases are improved by a gluten-free. 

I agree!  

I can completely sympathize with members who have odd celiac antibodies test results.  I only test positive to the DGP IgA (biopsy confirmed) which is really weird and I can find only a few studies that imply this can occur in the very young or elderly.  I guess I am elderly?  ?